Akademik Veri Yönetim Sistemi
JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM, cilt.25, sa.7, ss.2235-2238, 2012 (SCI-Expanded)
MgB2 film with a thickness of about 600 nm was deposited on the MgO (100) single crystal substrate using a "two-step" synthesis technique. First, deposition of boron thin film was carried out by rf magnetron sputtering on MgO substrates and followed by a post deposition annealing at 850 A degrees C in magnesium vapor. The upper critical field H (c2) has been estimated from temperature dependences of resistivity curves in both directions of the magnetic fields perpendicular and parallel to the c-axis. Resistivity measurements of the film were performed using a standard four-probe method under different magnetic fields up to 70 kOe in zero fields cooling regime. The upper critical magnetic field H (c2)(0) at T=0 K for 90 % of R (n) was calculated by the extrapolation H (c2)(T) to the temperature T=0 K. The results showed that H (c2)ayenab(0) and H (c2)ayenc(0) was found to be around 22 T and 18 T, respectively. Using extracted data, the zero-temperature coherence lengths and field anisotropy ratio were calculated. In order to determine the activation energy of thermally activated flux flow of the film, Arrhenius law was taken into account.